Overnight, the outspoken rapper used the very popular ALS Ice Bucket Challenge as an opportunity to dare boxer Floyd Mayweather Jr. to prove he could read.

“This is a special [ALS/ESL] challenge for you, Floyd,” he said in a video posted to his Instagram account, which you can view at the bottom of the page.

“If you can read one full page of a Harry Potter book … I’ll give $750,000 to whatever charitable organisation you want to.

“ ... without starting and stopping or f***ing up,” he added.

Rapper 50 Cent.Source:Supplied

The challenge is the latest chapter in the long-simmering beef between the former friends.

50 Cent, real name Curtis Jackson, has taken much delight in poking fun at Mayweather and his recent romantic troubles, taking every opportunity to remind the undefeated fighter that his ex-fiancée, Shantel Jackson, left him for the rapper Nelly.

The boxer addressed his many feuds — including the one with another rapper, T.I., who he brawled with at a Las Vegas Fatburger earlier this summer — in an interview with MLive yesterday.

“God has blessed me with an unbelievable talent, with fast feet, fast hands, unbelievable defence and a very, very sharp mind. So I’m thankful for that. Of course, hip-hop artists, they come and go. They come and go. But I’m still here,” Mayweather said.